It is known to provide conduction among electrically conductive layers of a printed circuit board by forming a through-hole with an electrically conductive sidewall, which is called a via hole, on the printed circuit board. The space between via holes formed on a printed circuit board has been narrowed by reducing the size of electronic equipment, and, in some cases, a solder bridge is formed between the lands (portions of the electrically conductive material of the via holes exposed in a doughnut shape on the surface of the printed circuit board) of adjacent via holes during soldering. In addition, particularly in the vicinity of a portion of the printed circuit board where the heat capacity is large, in some cases, a solder ball is formed on the land of a via hole during soldering. When the solder bridge or the solder ball is separated and moved away from the printed circuit board due to some sort of shock or the like and short-circuits the wiring of the printed circuit board or the lead wires of components after the printed circuit board is incorporated into electronic equipment, the electronic equipment may malfunction. It is known to prevent the formation of the solder bridge or the solder ball by applying solder resist on the lands of all via holes that are not used for mounting of a component such that the solder does not adhere to the lands of the via holes during soldering (see, for example, Patent Document 1).